A list of elements

The horizontal rows are called periods and the vertical columns are called groups. Each group contains elements that have the same number of electrons in their outer shells. For this reason, they have similar chemical properties. Each element has a higher atomic number than the element to its left.

The lanthanide and actinide series (purple) are normally displayed below the rest of the Periodic Table, for reasons of clarity. The arrows show where these elements fit into the table.

Between the metals and non-metals are the semi-metals. These have some properties of metals and some of the non-metals. For example, arsenic looks metallic, but it is a poor conductor of heat and electricity.

On the right of the table is a non-metal group called the halogens: fluorine, chlorine, bromine, iodine and astatine. Their atoms each have nearly a full set of electrons in their outer shells and thus can easily gain an electron to form negatively charged ions. So these elements, too, are highly reactive: they easily form bonds with other elements.

Glossary of terms

Actinides A group of radioactive metals. They are transition metals.

Alkali metals A group of metals that react with water to form alkaline solutions. All alkali metals have just one electron in their outer shell. They are generally soft, shiny and a pale silvery colour.

Alkaline earth metals A group of metals that have two electrons in their outer shell.

Atomic mass The average mass of one atom compared with the mass of one carbon atom.

Atomic number The number of protons found in the nucleus of an atom.

Chemical symbols Letters that are used to represent a chemical element. For example, C represents carbon and Cu stands for copper.

Element An element is a substance made up of atoms of the same type. It cannot be broken down into simpler substances. Different elements have different characteristics, which are determined by the number of subatomic particles they have. There are approximately 100 natural elements known to us. These are divided into metals, non-metals and semi-metals.

Halogens A group of non-metallic elements with similar characteristics. They easily form bonds with other elements.

Lanthanides A group of silvery metals with very high melting points. They are sometimes called the “rare earth metals”. They belong to the transition metals.

Noble gases A group of gases that have similar characteristics. They are sometimes known as the inert gases because they do not easily form compounds with other elements. One common noble gas is neon, which is used to make lights and street signs. Because it does not react with other elements, it will not ignite or explode.

Poor metals The name sometimes given to a group of soft, weak metals that melt at low temperatures.

Semi-metals Otherwise known as the metalloids, the semi-metals are a group of elements that are neither metals nor non-metals. Typically they have the hard, shiny appearance of a metal, but make poor electrical conductors.

Transition metals A group of metals that are mostly hard, dense and shiny and make good electrical conductors.

Consultant: Nina Notman